Fix GetBranch response

[isqua]

I want to get a time of the last commit in branch. I read Github API: Get Branch docs and found the RepositoriesService.GetBranch method. I called it like so:

client.Repositories.GetBranch(orgName, repoName, branchName)

But get the following data (e.g. for this repo):

{
	github.Commit {
		SHA:"5c45bca952b96dedace6c307caff915483013003",
		Author:github.CommitAuthor{},
		Committer:github.CommitAuthor{},
		Parents:[
			github.Commit{
				SHA:"5c5ff1dadae3bb0b306004d480a88e7ddc1714ca",
				URL:"https://api.github.com/repos/google/go-github/commits/5c5ff1dadae3bb0b306004d480a88e7ddc1714ca"
			}
		],
		URL:"https://api.github.com/repos/google/go-github/commits/5c45bca952b96dedace6c307caff915483013003"
	}
}

As you see, the Author and Committer fields has no info. I tried to call the endpoint with curl:

curl -H 'Accept: application/vnd.github.v3+json' \
     -H "Authorization: token ${MY_GITHUB_TOKEN}" \
     "https://api.github.com/repos/google/go-github/branches/master"

And get data I expected:

{
  "name": "master",
  "commit": {
    "sha": "5c45bca952b96dedace6c307caff915483013003",
    "commit": {
      "author": {
        "name": "Ronak Jain",
        "email": "ronakjain@outlook.in",
        "date": "2016-12-09T18:12:45Z"
      },
      "committer": {
        "name": "Glenn Lewis",
        "email": "gmlewis@google.com",
        "date": "2016-12-09T18:58:51Z"
      },
      "message": "improve docs ...",
      "tree": {
        "sha": "de558bd3716b5304a7d40e90c4871a5173ac40a2",
        "url": "https://api.github.com/repos/google/go-github/git/trees/de558bd3716b5304a7d40e90c4871a5173ac40a2"
      },
      "url": "https://api.github.com/repos/google/go-github/git/commits/5c45bca952b96dedace6c307caff915483013003",
      "comment_count": 0
    },
    ...
  }
}

Looks like commit at the root of response is a RepositoryCommit.

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[isqua]

I signed it!

[googlebot]

CLAs look good, thanks!

[dmitshur]

You're absolutely right. It was surprising to me that we'd have such a glaring error, so I dug through git blame to see how it occurred (in order to make sure I'm not overlooking something).

It seems we've had the issue since its very initial implementation in 2014. From that commit, I have a pretty good of how it happened. ListBranches was implemented first, and Branch type was created for it.

If you look at https://developer.github.com/v3/repos/branches/#list-branches, you'll see the example that the list endpoint provides has only "sha" and "url" fields inside the "commit" object. A coincidence is that both Commit and RepositoryCommit have those fields, so it's easy to use one instead of the other.

GetBranch was added later and seemingly no one else ran into this (or reported it) until now.

Thanks for the patch!

[dmitshur]

LGTM.

[dmitshur]

This is good, but I think it's a good opportunity to expand the test data to include a Commit inside. That way it'd be a little more representative of the real data you get from GitHub, ala https://developer.github.com/v3/repos/branches/#get-branch.

Something like this:

want := &Branch{
	Name: String("n"),
	Commit: &RepositoryCommit{
		SHA: String("s"),
		Commit: &Commit{
			Message: String("m"),
		},
	},
	Protected: Bool(true),
}

You'd have to update the mux.HandleFunc("/repos/o/r/branches/b" above, of course.

Doing this is optional, if you agree it'd be an improvement for this Go package.

[isqua]

Well, I’ve done it: 7920789

[dmitshur]

Looks great, thanks!

[gmlewis]

Thank you, @isqua and @shurcooL!
LGTM. Merging.

[gmlewis]

Included in a77ccc9.